The present invention relates to an injection molding machine with at least one actuating drive in the form of a spindle drive and an energy storage device associated with the spindle drive, and more particularly to an injection molding machine which is able to generate large acceleration and deceleration forces at stroke inversion points while keeping the energy consumption of an electric drive motor low.
International patent publication WO 97/34757 discloses a spindle drive with an electric motor operating as an actuating drive for an injection molding machine, and an energy storage device in the form of a compression spring arrangement operating in parallel with the spindle drive which relieves the electric motor in a feed motion phase. The load on the compression spring arrangement is increased during the return stroke and produces during the spindle feed motion an amplified force which decreases continuously in conformance with a characteristic spring curve.
Conversely, actuating drives employed for cyclical actuation of an ejector with a relatively high operating frequency or drives used to move large masses back and forth, for example the linear drive for the plasticizing unit, have to generate large deceleration and acceleration forces at the respective stroke inversion points. Conventional actuating drives can generate these forces only with the help of powerful electric motors, resulting in a correspondingly high energy consumption.
It would therefore be desirable and advantageous to provide an improved spindle drive in an injection molding machine, which obviates prior art shortcomings and is able to specifically generate large acceleration and deceleration forces at the stroke inversion points while keeping the energy consumption of the electric motor low.